Cooking apparatus



Jam.23,194o.- NACHUMSOHN y 2,187,888l

COOKING APPARATUS Filed May 2l, 1936 v 3 Sheets-Sheet 1 MEAT A j .27W MM50/Ua. mxmz par Prisa fum.

Jan. 23, 1940. NAcHuMsoHN COOKING APPARATUS Filed May 21, 1936 3 Sheets-Sheet 2 Jan- 23, 1940. .1. NAcHUMsoHN 2,187,888

` COOKING APPARATUS Filed May 21, 1956 s sheets-wiegt 5 Patented Jan. 23, 1940 UNITED STATES PATENT OFFICE Application May 21,

9 Claims.

My present invention relates to a method and means for cooking electrically and more particularly it involves the method of cooking by means of an electrically operated appliance the latter of which is more specifically of the portable type.

In one respect the apparatus shown in the present embodiment is comparable with a class of cooking devices now known to lthe, public as electric roasters. However, as the speciiication 10 progresses it will readily become manifest that numerous cooking applications other than mere roasting maybe carried out with my invention by virtue of the features of novelty incorporated therein.

One object in my invention is to provide an improved cooking means capable of meeting the diversified phases in the general art of cooking, such as baking, searing, scalloping, steaming, stewing and so forth. A further object is to provide portable apparatus of the class described having new and useful features of construction and operation.

An important `object of my present invention is to provide a portable electric roaster which positively overcomes, as expert cooking tests have proven, some of the objections existent in devices of this class in use heretofore. Considering suoli last named devices, it is well known that there is much to be desired by way of results from a scientific cookingangle; such results being much less satisfactory than those obtainable when similar foods are heat treated in gas, electric or other ranges of the larger and less portable type.

. Considering electric roasters in use heretofore, their inherent shortcomings as compared with larger ranges are particularly noticeable when they are used to Yroast a fowl or other meats. AOne of the reasons for this is due to the fact that with the larger and less portable ranges, the problem of heat distribution by way of conduc- 40 tion, convection and/or-radiation in order to treat' all parts of thefood in proper proportions is not so serious. This, because whena conventional oven roastpan containingy the food is put into the comparatively large ovens the entire roastpan and food contents including even the lid occupy a relatively small portion Jin the. oven and possess comparatively little mass next to the heated bulk comprising the oven and stove. Hence, if the covered roastpan is placedsomewhat central in the oven and the heat distribution in the latter is even moderately uniform, the problem of treating all portions of the food properly is not so difficult. With an electrically operated roaster of the portable class'however, the problem of distributing heat to all portions of the food contained in the food compartment is considerably more didicult because for reasons of compactness, efllciency as well as economy, it is essential that a more intimate relation be em` 193,6, Serial No. 80,948

(CL 21S-35) ployed between the source of heat and the food to be treated thereby. l

In the roasting of meats and other foods it is desirable that they are properly browned or seared and one of the disadvantages in the older' type roasters above referred to resides in the fact that in order to brown or sear food prior to the subsequent and slower step of roasting, it has been necessar'y to partially or wholly fry such foods. This is exemplified by the fact that with such devices even the manufacturers thereof recommend browning a roast by turning the latter over several times in the preheated vessel in order to brown thesurfaoes of same. This procedure, in a true cooking sense, actually constitutes frying because browning or searing, as such, is accomplished by the drying effect on the surface of the food due to the application of heat other than by direct thermal contact between iood container and food; the latter beingl the process which prevails ywhen using the conventional frying pan over a` heat source.

Electric roasters. are desirablyl compact and light for the sake of portability and by virtue of their general design possess relatively little thermal inertia or heat storage capacity as compared with larger ovens of stoves or ranges. For this reason it is important to obviate the necesvsity of `:lrequent handling and close Watching of the food being cooked in an electric roaster since each time the lid of the latter is removed the internal temperature will d rop rapidly, introducing attendant disadvantages in cooking by way of time and results.

Therefore, in carrying out an important object of this invention, the structure and arrangements of parts as well as the thermal values therein are such as to enable the attainment of more satisfactory results than with older types of electric roasters. For example, tests have proven that it is possible to place a fairly large portion of meat to be roasted in this unit, adjust th' thermostat to predetermined value or values and after a given period of time produce a properly browned or seared roast without frequent removal of the cover of the oastpan. Thus, `excessive heat and steam are not permitted to escape and less frequent attentionY or cooking experience is necessary.

To the attainment of these and numerous other objects and advantages which will 'become o'o vious as the specification progresses, my invention consists in the features of novelty described herein, illustrated in the accompanying draw. ings forminga part hereof and more particularly pointed out in the appendant claims.

In the drawingsillustrating a preferred form of the invention, Figure 1 is a front elevation of the assembled apparatus; Figure 2 is an enlarged fragmentary showing of the apparatus as w illustrated in Figure 1 with wan portions broken away progressively to illustrate the general arrangement of the parts. Figure 3 is a sectional plan View, looking downwardly along the line 3-3 of Figure 2; Figure 4 is an enlarged fragmentary view of the side wall and illustrates the improved form of heating element employed in the side walls Aofthe apparatus; Figure .5 is afragmentary view of the electric heating element employed to heat the bottom surface of the cooking vessel; Figure 6 is a vertical section taken along lines 6-6 of Figure 1; Figure 'l is the wiring diagram showing the'electrical circuit employed and Figure 8 illustrates one of the many possible cooking charts which may be used in carrying outone or more of the aforementioned 'Referring now particularly to Figures 2, 4 and 6, an outer pan 6 may be seen which houses the roastpan I and it is made somewhat larger than the latter. Unlike with the roastpan, the shell 6 has a square U-shaped cross-section the purpose of which is to provide a greater space between thesetwo pans at 'the point 'I `between their respective corners for reasons hereafter described.

The shell 6 has wound therearound an elec trical heating element 8, said element being insulated from the shell by a band of insulating material 9 comprising mica, asbestos or any other suitable substance.

I have found by employing a hat ribbon resistance element, instead of round wire, that several advantages are gained. In

the winding of the resistance ribbon around the side walls of the inner shell, which operation is done before said shell is assembled to the other parts, it is preferable to rst wrap thisA shell with the insulator 9 and thereafter to spiral the spaced windings tightly around the insulated periphery. Thus, by employing a ribbon element a greater tension may be exerted during the winding operation with, less tendency for the winding to cut into the-insulating band. At

the same time the vtension thus gained provides a more intimate thermal relation between the resistance element and fthe container 6 \With considerably more area of contact between th elements due to 4the flat surfaceof 'the ribbon,`

and a consequent reduced thermal drop therebetween.

For pr per browning or searing of. a Vroast or other foo s as heretofore explained I have found that it is highly desirable to. provide a denite portion of purely radiant heat properly focussed on the food. This provision' partially obviates the-necessity of frequent attention and turning of the foodv during the cooking process and with the other values of conducted and convgcted heat properly proportioned I have fo d that a preparation of food may be cooked .evenly and properly browned without human attention'.

As. shown in Figures 2 and 4 such a source of radiant energy is provided Vin the uppermost y convolution 8A of the element 8. The ribbon element 8 (see Flgugem is imbedded in a ceramic it will-be seen that this is accomplished by the or other electrically insulating cement 8B, this expedient serving to retain the convolutions of resistance wire in permanent spaced relation; and it is preferable to coat the completed winding, with the exception of the portion 8A thereof, 5

Withasbestos or vliquid porcelain substances well known in the art. By thus providing a plastic coating of insulating material on the completed winding and drying the same before the elementsupporting shell 6 is assembled to the remaining parts, said coating protects the element during handling and permits an outer wall of heatresisting material to be packed therearound without disturbing the windin proper. The cement 8B is shown only aro d the lower half of the winding 8, the upper turnsbeing shown exposed for illustration purposes only.

In order that a portion of the heating unit, such as 8A, may act to convey radiant and reiiected energy to the food, provision is made whereby a plurality of paths for said energy, lead into communication with the food placed in the cooking pan- I. Referring now to Figure 4 provision of an annular row of rectangular windows, oropenings 6W, disposed in a 'series adjacent the upper edge of the element-supporting vessel 6, said openings being located so as to permit the upper winding IA to extend centrally and longitudinally of the series. In order that the element 8A be also electrically insu lated from its support 6, the insulating band i is comb shaped, the upper edge thereof terminating in a series of lugs or. teeth I0 which occur in alteration with the windows Bi.

Whereas the element 8 is virtually imbedded in a refractory material and its temperature is therefore kept comparatively low due to the thermal conductivity of the relatively dense mass surrounding the individual turns thereof the element 8A, even though it is of the same crosssection as the turns 8 and connected in series therewith so as to carry the same current, is permitted to attain a much higher temperature at the portions II thereof because said portions are'suspended in air the thermal conductivity of which is relatively low. In operation. the portions II may be made to attain even a dull red visible glow while the turns 8 are kept oonsiderably below this temperature because the dense or solid substance surrounding the latter comprises a more emcient thermal conductor which thus conducts the heat to the wall B.

' With the above described arrangement a continuous'complete winding establishes two sources 'of heat; one, a spread out or diffused source of conducted heat which is uniformly distributed peripherally throughout the maior area Acomfrom a plurality of individual points II. Howy ever, incarryingy out some of the 'enumerated' objects of my invention' the mere provision of two sources of heat is not adequate. as will hereinafter appear, for the distribution; of eachgg source of heat to the proper locations as well as in correct proportions.

Aband of'metal I2, ovalled in a, uniformly` spaced relation around the' element-supporting'- member 6, serves as the outer casing of the de- 7gvice. An oval frame Il made .ei er of a casting or a metal stamping is provi ed. Said frame has an inverted U-shaped cross-section the parallel side Walls of which 'serve to maintain a uniform separation between members 6 and I2, 75

the space therebetween comprising a hollow wall in which is packed any of the well known heat insulating substances i4, such as asbestos fibres, mineral wool or the like. In order to cbmplete the enclosure necessary for the outer casing an oval-shaped bottom i5 is provided. 'I'his bottom may be fastened to the outer band i2 as` shown at i6, Figure'2. A relatively short band of metal i1 comprising an ornamental skirt, may be employed around thev lower edge of the band i2 to embellish the device. Four vertical strutv posts it may also be used to draw the frame member I3 tightly against the band i2 in which kcase the upper ends of these posts may be provided with threads adapted to screw into tapped holes in the horizontal wall of the member Il.' If the latter is of cast metal, depending bosses i9 cast integrally therewith and having tapped holes may be provided to receive the upper ends of the strut posts.

In order to facilitate the distribution of heat to the food in the proper proportions referred to an extra ilat heating unit clearly shown in Figures 3, 4 and 5 is provided, said element being disposed in close thermal relation to the bottom of the element-supporting vessel C. I'he ribbon resistor "Z0 constituting this element is wound on a sheet of refractory. material 2|, such as assections, series-connected by a central portion 23 thereof and terminating at ends 24. A plate of heat-resisting insulation 2l serves to prevent the metal bottom 6A from short-circuiting the wires 20 and another similar plate 26 may be disposed on the opposite side of the element-4 supporting plate Zi. This bottom element should be held firmly to the bottom IA in any suitable manner. One method for accomplishing this is to cement the three plates as a unitand thereafter to cement, clamp or rivet this'unit to the bottom BA. In any event the insulation packing i4 further serves tov press the unit upwardly.

One reason for dividing the bottom yelement into two separated halves is to provide a means to' compensate for` the oval shape of the entire device. In the absence of a suitable compensating medium, certain shaped foods centrally located within 'the cooking compartment will have a tendency to cook or bake faster along the opposed parallel front and back sides of the compartment. This is readily made manifest in practice by baking a pie or cake in the device. k.it fairly large round pie, centrally placed Pin Figure 3, will ordinarily bake more rapidly at the portions where the periphery comprising the solid crust thereof occurs closest to the oval shaped wall of the food compartment. By thus separating the lowerelement into two halves the extreme ends oi the oval compartment are given an added source of heat which applies to the end portions of the food, baking the latter uniiormly. During baking it may be desirable to butfinverted dishes or pans, or on an elevated wire rack,y or shelf, not shown.

YIn addition to the electrical heating elements thermostatic bi-metal 28, a thermo-responsive `5 contact-supporting spring 29 and a manually adiustable but similar contact-spring 30. Thesel spring contact tongues support a pair of co-operating contact points 2i, in a well known manner.

The 'entire contact tongue and bi-metal assembly 10 ,comprising this thermostat is supported from a 'unitary U-shaped electrically insulating base member 32 made oi' porcelain or any other suittable heat-resisting material. The thermostati is connected between one of the current supply 15 wires 33 and theheating elements, the other circuitous end of the latter terminating a second current supply wire 34. The thermostat assembly Ais enclosed in a metal case 35 and a strip of metal possessing high thermal conductivity serves 20 A to maintain an intimate thermal relation between the thermostat and the bottem 8A of the element-supporting vessel.. This may be accomplished by inserting one portion of the metal strip $4 between the insulating sheet 25 and the 25 bottom 4A, the other end portion of said strip being wrapped around or otherwise thermally and' mechanically fastened tothe case 35. The latter maybe further fastened to the bottom 6A by means -of screws or rivets not shown.

Inorder that a user of the apparatus may-get the device to operate at any desired temperature, a manually adjustable control member 31 is provided. Baid member is slidably disposed on a horizontal rod 38 which is supported at its ends 35.

from opposed wall portions 39 formed integrally with the band i 2. 'Ihe vertical wall portions 22, a similar drawn out horizontal wall formation 4l,` together with a rear wall plate 4i spotwelded to band i2 comprise a'y rectangular box- 40' like enclosure into which temperature regulation J and indicating apparatus is placed. A door 42, made transparent by a glass window 43 therein, is hinged for opening; the extreme ends of the slide rod 438 forming two pivoted supportsthere- 45 for. f l

The adjustable `slide 31 is formed to present an integral vertical pointer 44 adapted to ind1\ cate the temperature at which the device is set, l

by lindexing ,on a suitably calibrated temperature indicating scale 45, said scale being etched into or otherwise disposed on the glass window. The control member 3l is also provided with an integral horizontal portion i6 extending towards the body of the apparatus and comprising a' shoe adapted to slidably engage a lever 48. This lever is pivotally supported from plate l as shown at 49 and is adapted to co-operate with the slideshoe d8 in such a manner as to enable the particular horizontal position of the slide to determi-ne the angle which the lever 48 will -describedwith respect to the plate. This angular adjustment. in turn, determines the hori-r xontal movement of a.plunger pin 50, the uninsulated end of which buttsagainst the inner face ofthe square lever 4B and the inner insulated end ti of which likewise presses against the contact-supporting tongue 30. The tension in the latter serves to at all times maintain a yieldable and therefore adjustable mechanical connection between the tongue 30 and the control member 3l' so that a movement of the latter to the right, for example, will, through the structure just described, cause the contacts to close. The

spring ab m with a forward tension 75 t which normally tends to bring the -i'ront contact forward tension so that it is at all times in yieldable contact with the curved end of the bi-metallic strip 28. In line with thermostat design, the tension of spring 29 should not be so great as to impose an excessive load on the bi-metal for the latter must be free to ilex in response t'o changes in temperature.

As shown in Figures 2 and 8, the device Amay be provided lwith a plurality of cooking charts 53 comprising removable cards or etched metal plates adapted to be selectively inserted into the rectangular enclosure by opening the small' door thereof. As shown to thel left of each chart, they are tabulated to indicate the general class of foods listed thereon. 'I'he respective foods are grouped horizontallyalong the chart so that each groupl will lie adjacent a corresponding temperature indication on the scale that it is l recommended to cook such foods at. Thus, it will tion of the metal parts which might tend to change the relation between the apparatuscontained in these two enclosures is prevented by virtue of the rigi d con'necting medium 55 there between which, at the same time, ,serves to pro'- tect the slide pin therein trom the packing or insulation surrounding it where it extends transversely through the walls.

-With the abovev described arrangement it will be observed that I have combined -temperature vsetting and indicating apparatus with pre-arranged andpre-calibrated-cooking charts in such a manner that a novel combination is 4effected ,and that new and useful results are obtainable thereby. `pposite each food item printedon a given chart is a, ligure which represents the length oftime, in minutes or hours,A that .the specined quantity of food requires. cooking. '.l'liierei'ore,l in the use of the device it is not es-v sential that the user'thereoi have any knowledge of cooking since it is only necessary-to place a given food or food preparation into the'device.- move the control vmember '31 (which when in the "ofP position tothe extreme left opens the contacts) to the right until the pointer thereorfaus 4 into registration with the index under which the particular food to be cooked is listed. Thus-no knowledge of temperature nortime requirements for a.A given food is necessary, for the temperature is automatically selected when the food is indexed and the cooking time for that particular food is then instantly readable opposite the food thus indexically selected. While for the purpose of this patent-I have shown and described a speciilc form of temperature control and indicating apparatus coupled with a method of setting the apparatus with one or more food charts which in effect constitutes an electric cooker with a.

built-in cookbook; and while the workable arrangement is described in sufiicient detail for a mechanic skilled in the art,v said apparatus is more specically described and claimed in my copending application for patent, 4Serial No. 162,208. r

A pilot lamp 56 is disposed within the cook book compartment so as to illuminate the exposed cooking chart, making the latter readable through the glass Window 43. For purposes of safety said lamp is of the low voltage' flashlight bulb type and current therefor is derived by virtue of the potential drop across the section 23 of the Lbottom heater. Ordinarily a device of this character might be operated on a voit, 60

cycle A. C. lighting or power circuit. With thev pilot bulb potential derived from spaced points adjacentI the electrical center of the element, should a person obtain a shock bycontact between a possibly exposed portion of the lamp base or any other live conductor and ground, the voltage therebetween would not be much above 55 volts. This expedient provides a safety measure against electrical shocks. A pair of wires 23h leading from the lamp completes the lamp circuit to the section 23 through a corresponding pair of terminal lugs 23A connected across the latter.

With particular reference to Figure 7 it is to be noted that the heater circuit comprises two parallel-connected halves. By virtue of the relatively large periphery of the side wall of the element-supporting vessel, as compared with the bottom thereof, coupled with the fact that the ribbon resistor is, of the same cross-section throughout the device, the major part. of the `winding is adjacent the side walls. Thus, in order that1 both parallel halves of the heater circuit shall possess substantially the same resistance it is necessary that the side heater be tapped for connection with line wire 34 towards one end of the side heater, as shown at 51. The other line wire 33 is connected to the heater circuit through the thermostat contacts and a resistor r of relatively high value may be employed to minimize arcing betweenv said contacts. l

. In the operation ot the device the p'ilot lamp serves the dual purpose of first illuminating the exposed page of the loose-lea! cock book the mo-f ment the control knob is pushed to the right` exact vposition required. Then the lamp continues to burn steady only until the temperature within the cooker increases to the point selected by virtue o! the-food indexed, whereupon the lamp ilashes on'and oi! intermittently with the thermostat action. The intermittent 'flashing therefore serves to indicate that the proper temperature has been reached and is being maintained. Thus the4 reading of the cook book occurs under desirably steady illumination whereas the intermittent illumination, which is objectionable for reading purposes, does not commence until afterthe chart has been read.

With reference to Figure 6 it will be noted that radiant energy emanating from element 8A travels as indicated by straight broken lines. In this connection a reflector 58, comprisinga series of annular channels made of .aluminum or other suitable material, is disposed to the rear oi the element 8A. so that the radiant energy directed and permitthe radiant energy to pass freely into 1| i towardsthe rear of said element will be reflected ,n

the food compartment. A cover or dome 50 removably fits into the upper portion of the vessel I by adapting the rim of the former to rest upon the horizontal shoulder 5. The inner surface 6| 5 of the cover is coated preferably with a white or `other light color vitreous enamel so that any heat energy directed'upwardly will be reflected downwardly upon the food as indicated by the straight broken lines.

To further compensate for and with the view of minimizing the heat conveyed to the food by direct thermal contact between the food container and food, a vent 62 may be provided. This is shown in the form of an elongated tubular eyelet which extends transversely through the lower heating element, the inner bottom 6A and the outer bottom I5, and provides a port into which cold air may be drawn upwardly and circulated around the outer surface of the vessel as indicated by the heavy arrows. This effect due to convection serves to bring the initial cold air into contact with the middle of the vessel i first,

whereupon said air spreadsA radially in all directions, passes upwardly between the vessels i and 6, entering the latter through windows 59 and nally leaving the vessel through one or more openings dit. IThe openings are made adjustable by means of dempers 65, in a well known manner.

The above described expedient improves the emciency of the apparatus in several ways. First it provides a compensating medium similar to` that edected by splitting the lower element into 'two halves for the purpose heretofore described. Secondly, it compensates for the thermal advantage-that the lower portion oi' the food ordinarily possesses because of its intimate contact with the bottom Aof the 'cooking vessel, by chilling the entire lower portion of the vessel to a greater degree than the side walls thereof, since the air currents become hotter as they progress through the device. rThirdly, this expedient provides an adjustable medium for circulating air through the apparatus where, in the .cooking of certain foods, it may be desired. In this latter respect it is to be noted .that the cooking effect of the radiant heat may be increased in proportion to the convected andconducted heat, since by merely opening the vents 65 the total effect of the latter forms of heat are minimized by virtue of the air circulation while the radiant heat remains relatively constant.

The device may be finished byproviding the dome with a handle 61. Portability of' the apdil) paratus as a unit is facilitated by the provision 55 of a pair of sidev handles 68 fastened to the outer hand.v Opening the door of the cook book com- Ipartment may also be facilitated by the provision of a small knob 69 cast integrally with the frame structure B2. Finally, the bottom may be provided with feet 'l0 fastened to the vlower ends of the strut posts i8.

I claim:

l. In portable cooking apparatus, the combination with a 'substantially rectangular shaped 65 cooking vessel terminating upwardly in a peripheral rim which rim is disposed in a horizontal uplane, said vessel having closed side wall and bottom portions, a raised cover for said vessel having a depending rim adapted to engage the 'w peripheral rim of said vessel to form a substantially closed cooking compartment, a source of heat distributed in desired proportions about said l side wall and bottom portions of said vessel and a plurality of openings arranged in'annular series towards'the upper portion of said side wall portions and adjacent said peripheral rim.

2. Ina device of the character described, the combination with a receptacle having an electric heating element in intimate thermal relation with the periphery thereof; of a cooking vessel within said receptacle disposed for removal upwardly therefrom; and having a substantial air space between said receptacle and vessel to provide media for a thermal drop therebetween; and additional heating elements adjacent the bottom of said receptacle providing a plurality of heated zones spaced apart so as to ycreate a relatively colder portion in said bottom towards the center thereof.

3. In a device of the character described, a receptacle having an electric heating element in thermal relation therewith, a cooking vessel within said receptacle and removable upwardly therefrom, said vessel having a plurality of openings adjacent the rim thereof, an air space between said receptacle and vessel including an atmospheric air inlet therebelow in communication with the said air space and said openings and a dome for said device having means for permitting escape oi' air rising upwardly through said openings.

4. In a device of the character described; a receptacle, an electric heating element comprising a source of heat adapted to heat the interior of the vessel through the walls thereof, another heating element comprising another source of -heat disposed adjacent the side wall of said receptaclemnd adapted to directly heat the interior of said receptacle, a reflector disposed to the rear of said last-named element and adapted to reiiect heat from the latter into said receptacle, a cooking vessel disposed within said receptacle for removal upwardly therefrom and adapted to be heated by both said sources of heat, and a cover for said cooking vessel having an inner reflecting surface for further directing said reiiected heat into said vessel.

5. An electric cooker comprising a receptacle, an electric heating element confined in the lower portion of the sides thereof and effective to heat the lower interior of the receptacle by conduction, and an exposed electric heating element carried by the receptacle in proximity to the upper portion of said sides to heat the upper interior of the receptacle by radiation, said upper portion of the receptacle sides being perforated opposite said exposed element.

6. The structure of claim 5, said exposed element having a horizontal course along said sides, and reflecting means along said course to concentrate the heat from said exposed element in the direction of said upper interior.

"7. 'Ihe structure of claim 5, said exposed element having a horizontal course along said sides, and a channel-shaped reiiector along said course to concentrate the heat from said exposed element in the direction of said upper interior. 8. The structure of claim 5, said exposed element being a strip having a horizontal course along said sides, and a channel-shaped longitudinal reiiector facing inwardly to dispose said stripin the directionof said upper interior.

9. The structure of claim 5, a food vessel spacedly disposed within the receptacle, andv means to vary the proportions of heat from said elements by air convection in the space between the rey ceptacle and vessel.

IRVING NACHUMSOHN. 

